Patient monitoring system

ABSTRACT

A wireless medical telemetry system includes at least one wireless patient monitor configured to monitor a patient by collecting vital signs data from the patient, and a first central station associated with one or more wireless transceivers, and adapted to establish communications with the at least one patient monitor and receive the vital signs data via the one or more wireless transceivers. A second central station is associated with the one or more wireless transceivers, and adapted to receive vital signs data via the one or more wireless transceivers. The second central station is configured to automatically attempt to establish communications with the at least one patient monitor and receive the vital signs data in place of the first central station in the event the communications between the first central station and the at least one patient monitor are lost. There is also a method for monitoring a patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSerial No. 60/205,412, filed May 19, 2000 and entitled PATIENTMONITORING SYSTEM. The subject matter of this application isincorporated herein by this reference.

FIELD OF THE INVENTION

The present invention relates generally to monitoring the vital signs ofone or more patients, and more particularly to a system and method formonitoring patients via wireless communications.

BACKGROUND

Devices for measuring various physiological parameters, or “vitalsigns,” of a patient such as temperature, blood pressure, heart rate,heart activity, etc., have been a standard part of medical care for manyyears. Indeed, the vital signs of some patients (e.g., those undergoingrelatively moderate to high levels of care) typically are measured on asubstantially continuous basis to enable physicians, nurses and otherhealth care providers to detect sudden changes in a patient's conditionand evaluate a patient's condition over an extended period of time.However, since most hospitals and other medical facilities care fornumerous patients assigned to numerous different rooms, it can bedifficult for a finite number of clinicians to monitor multiple patientson a continuous basis. In an effort to alleviate this problem, somemedical monitoring systems have been developed to enable the vital signsdata collected from patients to be conveyed to a central location,thereby allowing one or a few clinicians to simultaneously monitormultiple patients in different locations. However, many of such priorsystems have not allowed the monitored patients to move about thehospital. Although a few “mobile” monitoring systems have beenattempted, such systems are difficult to use and prone to failureresulting in the loss of a patient's vital signs data.

SUMMARY

A wireless medical telemetry system includes at least one wirelesspatient monitor configured to monitor a patient by collecting vitalsigns data from the patient, and a first central station associated withone or more wireless transceivers, and adapted to establishcommunications with the at least one patient monitor and receive thevital signs data via the one or more wireless transceivers. Theinvention also includes a second central station associated with the oneor more wireless transceivers, and adapted to receive vital signs datavia the one or more wireless transceivers. The second central station isconfigured to automatically attempt to establish communications with theat least one patient monitor and receive the vital signs data in placeof the first central station in the event the communications between thefirst central station and the at least one patient monitor are lost.

The invention may also be characterized as a method for monitoring apatient that includes the steps of (i) establishing wirelesscommunications between a patient monitor and a first central station,(ii) collecting vital signs data from a patient at the patient monitor,(iii) communicating the vital signs data from the patient monitor to thefirst central station, and, if communications between the patientmonitor and the first central station are lost, (iv) automaticallyestablishing wireless communications between the patient monitor and asecond central station, and communicating the vital signs data from thepatient monitor to the second central station.

Other characterizations of the invention and the advantages of thepresent invention will be understood more readily after a considerationof the drawings and the Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, schematic illustration of an exemplary medicaltelemetry network according to the present invention in the context of ahospital.

FIG. 2 is a fragmentary, schematic diagram of a system for monitoring aplurality of patients in accordance with the present invention.

FIG. 3 is a front elevation view of an exemplary central monitoringstation according to the present invention.

FIG. 4 is a schematic diagram of an exemplary system for monitoringpatients according to the present invention.

FIG. 5 is a front isometric view of an exemplary patient monitoraccording to the present invention.

FIG. 6 is a front isometric view of another exemplary patient monitoraccording to the present invention.

FIG. 7 is a schematic, functional block diagram of an exemplary patientmonitor according to the present invention.

FIG. 8 is an exemplary image for display on a display screen accordingto the present invention.

FIG. 9 is similar to the image of FIG. 8 but modified to include amessage region for display on a display screen according to the presentinvention.

FIG. 10 is similar to the image of FIG. 8 but modified to include auser-interface for display on a display screen according to the presentinvention.

FIG. 11 is a flowchart illustrating an exemplary rendezvous processaccording to the present invention.

FIG. 12 is a flowchart illustrating an exemplary communicationsconfiguration process according to the present invention.

FIG. 13 is an exemplary image for display on a display screen, andincluding a user-interface operable to select a primary central stationin accordance with the present invention.

FIG. 14 is an exemplary image for display on a display screen, andincluding a user-interface operable to confirm a monitoringconfiguration in accordance with the present invention.

FIG. 15 is an exemplary image for display on a display screen, andincluding a user-interface operable to identify a patient beingmonitored in accordance with the present invention.

FIG. 16 is an exemplary image for display on a display screen, andincluding a user-interface operable to select a primary central stationin accordance with the present invention.

FIG. 17 is an exemplary image for display on a display screen, andincluding a user-interface operable to change alarm condition parametersin accordance with the present invention.

FIG. 18 is an exemplary image representing ECG data from a singleelectrode for display on a display screen according to the presentinvention.

FIG. 19 is an exemplary image representing ECG data from pluralelectrodes for display on a display screen according to the presentinvention.

FIG. 20 is an exemplary image indicating an alarm condition for displayon a display screen according to the present invention.

FIG. 21 is a schematic illustration of a system for monitoring a patientat plural central stations according to the present invention.

FIG. 22 is a flowchart diagram of an exemplary method for monitoring apatient at a central location in accordance with the present invention.

FIG. 23 is a flowchart diagram of another exemplary method formonitoring a patient at a central location in accordance with thepresent invention.

FIG. 24 is a flowchart diagram of another exemplary method formonitoring a patient at a central location in accordance with thepresent invention.

FIG. 25 is a flowchart diagram of another exemplary method formonitoring a patient at a central location in accordance with thepresent invention.

FIG. 26 is a flowchart diagram of another exemplary method formonitoring a patient at a central location in accordance with thepresent invention.

DETAILED DESCRIPTION

From an overview, and as will be described in detail below, a system andmethod for monitoring patients is described that affords communicationbetween plural patient monitors and plural central monitoring stations.The system and method is designed to allow the patient monitors tocommunicate with the central monitoring stations by using any knowncommunication connection (such as to-be-described access points) locatedanywhere using any known communications technology (such as the IEEE802.11 standard for wireless communication) that provides acommunication channel. The to-be-described system and method also makesit possible for a clinician to view patient data on a display componentof the patient monitor via any known communication channel such as theInternet. For example, the clinician could view patient data using knownweb browsers.

The to-be described system and method also includes a so-called“rendezvous process” of establishing communications with one or morecentral stations. As will be shown in connection with the description ofFIG. 11, the rendezvous process may be carried out in any of a varietyof different ways, and may vary depending on whether wireless or wiredcommunications are used, as well as on whether the patient monitor isestablishing a new communications connection or reestablishing priorcommunications which were lost or terminated.

The patient monitors of the to-be-described system are also constructedto function both as part of a network of patient monitors and centralstations, as well as stand-alone patient monitors.

Turning now to details, a system for monitoring patients according tothe present invention is indicated generally at 20 in FIG. 1. System 20includes one or more patient monitors 22, each adapted to collect vitalsigns data from a patient. System 20 also includes one or more centralmonitoring stations 24 adapted to communicate with the patient monitorsand receive, process and store the vital signs data. Thus, physicians,nurses and other health-care personnel (hereinafter referred tocollectively as clinicians) are able to monitor a plurality of patientssimultaneously and continuously from one or more central locations. Aswill be described in more detail below, patient monitors 22 and centralstations 24 are coupled to communicate using wireless transmissionswithin a medical telemetry network, thereby allowing a patient to moveabout inside or outside a monitoring facility without loss of centralmonitoring.

In the exemplary embodiments shown and described herein, system 20 isconfigured for use in a hospital. However, it will be appreciated thatsystem 20 also may be used in a variety of other environments including:(i) other types of medical facilities, research facilities, senior-carefacilities, hospices, field hospitals, etc.; and (ii) types ofnon-medical facilities and environments such as patient residences,retail stores, or patient locations outdoors. Therefore, it will beunderstood that the description herein encompasses medical telemetrysystems for use in all such environments.

System 20 may be configured to provide patient monitoring withinselected regions of a facility or throughout the facility. In theexemplary embodiment depicted in FIG. 1, system 20 is configured withpatient monitors and central stations on multiple floors of a hospital.System 20 includes one or more wireless transceivers 26 disposed withinthe facility and configured to communicate with patient monitors 22 viawireless transmissions. The wireless transceivers are configured toconvey communications between the patient monitors and the centralstations. As a result, centralized patient monitoring will extendwherever wireless transceivers 26 are disposed within a facility.

Transceivers 26 may be also be characterized as transmitter/receivers26, i.e. any device capable of transmitting and sending communicationsignals, whether it be a device operable for a wired application or adevice operable for a wireless application. However, for purposes of theremainder of the description of the exemplary embodiment, the termtransceivers will be used to describe for the wireless application beingdescribed.

Each floor may include a single central station (as shown on the upperfloor in FIG. 1) or plural central stations (as shown on the lowerfloor). Alternatively, a single central station may be configured tomonitor patients on multiple floors. In many hospitals, central stations24 are assigned to sections within the hospital that perform differentfunctions rather than to particular floors. For example, one or morecentral stations may be configured to monitor patients admitted to theIntensive Care Ward, one or more different central stations may beconfigured to monitor patients admitted to the Emergency Room, while oneor more other central stations may be configured to monitor patientsadmitted to the Maternity Ward, etc. Regardless of how the centralstations are arranged or assigned, system 20 may be configured to allowany patient monitor 22 to be monitored by any central station 24.

In addition to allowing multiple remote patients to be monitored at acentral location, system 20 may also be configured to allow cliniciansto view information about a patient's condition from various locationsinside and/or outside the hospital. For example, in the embodimentdepicted in FIG. 1, system 20 includes one or more annunciating devices28, each having a display adapted to identify a particular patient(e.g., by name, room number, etc.) and to provide some informationconcerning the patient's condition. Typically, annunciating devices 28are used to indicate alarm conditions for a monitored patient.Alternatively, the annunciating devices may be configured to indicatethe condition of selected patients regardless of whether an alarmcondition exists. In addition to annunciator devices 28, system 20 mayalso include other devices configured to enable clinicians to monitor apatient's condition at a location remote from either the patient or thecentral station. These other devices will be described in more detailbelow.

System 20 may be implemented in many different forms and configurationsusing various types and combinations of components to provide a varietyof features and functions within the scope of the invention. Forclarity, the invention will be described below primarily in the contextof one particular exemplary embodiment. However, it will be understoodthat the scope of the invention is not limited to the particularembodiment described, but rather extends to all such embodiments, forms,configurations, types and combinations.

Turning attention to FIG. 2, a schematic representation of exemplarysystem 20 is shown. The system includes a medical telemetry network 30adapted to monitor a plurality of patients. In the exemplary embodiment,network 30 includes a physical data transport structure 32 (alsoreferred to herein as a network) such as an Ethernet Local Area Network(LAN) system. Alternatively, network 30 may be any of the electricaland/or optical network communications structures known to those of skillin the art. Alternatively, physical data transport structure 32 mayinclude any other suitable network structure, including a wirelessstructure, whether now known or later developed. In any event, physicaldata transport structure 32 is adapted to interconnect a plurality ofnetwork components, and to transmit data communications between thecomponents.

Although not shown in FIG. 2, it will be appreciated by those of skillin the art that physical data transport structure 32 typically willinclude one or more devices adapted to connect the physical transmissionlines together and route communications within the communicationsstructure. Examples of such devices include switches, hubs, bridges,routers, and the like. Thus, as used her herein physical data transportstructure 32 includes all such devices which may be necessary and/orbeneficial to a particular implementation as well as the physicalcommunication lines.

Communications transmitted within network 30 typically comply with oneor more standard data communication protocols which are known to thoseof skill in the art. As will be described in more detail below, thecomponents of exemplary network 30 use a variety of standardcommunication protocols including the Transmission ControlProtocol/Internet Protocol (TCP/IP) suite, User Datagram Protocol (UDP),etc. Use of standard communication protocols allows a variety ofdifferent components to be connected to communicate over the network.Furthermore, use of standard communication protocols enables the use ofstandard routers, switches and other network devices as mentioned above.Alternatively or additionally, the components may communicate using oneor more non-standardized protocols adapted for medical telemetry or aparticular application.

Network 30 includes one or more central stations 24, each connected tocommunicate via physical data transport structure 32 and configured tomonitor a plurality of patients. It will be appreciated that centralstations 24 may take any one or more of a variety of different forms. Inthe exemplary embodiment, each central station takes the form of acomputer workstation configured to communicate via physical datatransport structure 32 and monitor a plurality of patients. Centralstations 24 may be any suitable type of central station such as theACUITY® central station available from Welch Allyn Protocol, Inc. ofBeaverton, Oreg. The ACUITY® central station is a version of theinvention claimed in U.S. Pat. No. 5,319,363 to Welch et al.

One example of a central station in accordance with the presentinvention is shown in FIG. 3. Exemplary central station 24 includes aprocessing module 34 having at least one processor (not shown) and atleast one data storage unit (not shown). The processor is adapted toexecute software stored in the data storage unit to communicate withpatient monitors, analyze patient data, etc. Central station 24 alsoincludes a plurality of display devices such as display monitors 36.Alternatively, central station 24 may include a single display monitor.In any event, display monitors 36 are connected to processing module 34and adapted to display vital signs data collected from a plurality ofpatients. Typically, central station 24 also includes one or more inputdevices 38 (e.g. keyboard, cursor control, mouse, remote control,touch-screen, etc.) operable by a user to control the central station.Central station 24 may also include one or more audio input/output (i/o)devices such as speakers, microphones, sirens, buzzers, etc., adapted toproduce an audible message to a user of the central station n. Those ofskill in the art will appreciate that central stations 24 may have avariety of different configurations within the scope of the invention.

Central stations 24 are typically disposed at selected centralizedlocations within the hospital such as at nursing stations, etc. Eachcentral station is adapted to receive patient vital signs data from oneor more patient monitors via physical data transport structure 32. Thecentral stations are controllable by a user to display selectedinformation concerning each monitored patient on the display monitor.This allows clinicians to view the information collected by a patientmonitor at the centralized location. Additionally, central stations 24may be configured to simultaneously display data from a plurality ofpatients, thereby enabling a single clinician to watch over severalpatients at different locations. In addition to communicating withpatient monitors, central stations 24 may also be configured tocommunicate with other central stations within the network. Thus, forexample, patient data received at one central station may be forwardedto a different central station. This allows two or more clinicians atdifferent locations to simultaneously monitor a single patient.Communications among different central stations will be described inmore detail below.

Turning attention back to FIG. 2, network 30 may also include one ormore database systems 40 configured to store patient information.Database system 40 is connected to physical data transport structure 32and accessible by central stations 24 to store and retrieve data.Patient information stored on database system 40 may include a varietyof information concerning each patient including personal information,medical history, room location, etc. Typically, the central stations areconfigured to access database system 40 to identify patients who areadmitted to the hospital and display a list of the patients on displaymonitor 36. This allows a clinician to associate vital signs datareceived from a particular patient monitor with the correspondingpatient. The central station also may be configured to store on databasesystem 40 some or all of the vital signs data received from the patientmonitors. While database system 40 is depicted in FIG. 2 as a single,separate system connected to physical data transport structure 32, itwill be appreciated that other configurations are also within the scopeof the invention. For example, database system 40 may be multipledatabases distributed around network 30. Alternatively, database system40 may be contained within some or all of the central stations.Typically, database system 40 is a system or network of data storagedevices, some of which are contained within the central stations andothers existing separately in network 30. In any event, it will beappreciated that database system 40 may be any of the various databasesystems or structures such as are known to those of skill in the art.

As discussed above, central stations 24 are configured to communicatewith a plurality of patient monitors via physical data transportstructure 32. Communications between the central stations and patientmonitors may be via wire (i.e., transmitted over a physical line adaptedto convey electrical or optical signals), or may be wirelesscommunications. Considering first the wire communications, one or morepatient monitors 22 may be connected to physical data transportstructure 32 either directly (e.g., through an Ethernet connection), orindirectly through a terminal server 42 or similar device. Terminalserver 42 includes a plurality of ports adapted to receive connectionsfrom the patient monitors. In addition, the terminal server is alsoconnected to physical data transport structure 32. The terminal serveris configured to receive communications from the patient monitors andforward the communications to the appropriate central station viaphysical data transport structure 32. Similarly, the terminal serveralso is configured to receive communications from the central stationsvia physical data transport structure 32 and convey the communicationsto the appropriate patient monitor. Terminal server 42 may be any of avariety of terminal servers such as are known to those of skill in theart. Any known wire or wireless communication technologies may be usedto perform the functions described above.

In TCP/IP based networks, communications between central stations andpatient monitors are directed to the appropriate component using networkaddresses such as IP addresses as well as hardware addresses. Typically,each central station is assigned a unique IP address and allcommunications to and from a particular central station will include theparticular station's IP address. Similarly, all patient monitors whichare directly connected to physical data transport structure 32 areassigned a unique IP address. In contrast, patient monitors which areconnected to physical data transport structure 32 through a terminalserver typically do not have a unique IP address. Instead, the terminalserver has an IP address with which to communicate with the othercomponents connected to physical data transport structure 32.Communications from a patient monitor are transmitted to the terminalserver with the IP address of the destination component (e.g., a centralstation). The terminal server appends its own IP address to eachcommunication and then forwards the communication to the appropriatecomponent. Similarly, communications to a patient monitor aretransmitted with the terminal server's address as the destinationaddress. Upon receipt, the terminal server forwards the communicationsto the appropriate patient monitor.

As shown in FIG. 2, network 30 also includes one or more wirelesstransceivers 26, which are hereinafter referred to as access points 26.Each access point is connected to physical data transport structure 32and configured to communicate with the other components connected tophysical data transport structure 32. Each access point includes thesoftware necessary to communicate via physical data transport structure32 using the selected communications protocols of network 30 (e.g.,TCP/IP, UDP, etc.). In the exemplary embodiment, each access point has aunique IP address that may be permanently coded into the access point,or may be assigned by a server such as described below. The accesspoints also are configured to communicate, via wireless transmissions,with components which are not directly connected to physical datatransport structure 32. Each access point includes a wireless receiverto receive wireless communications, and a wireless transmitter totransmit wireless communications.

It will be appreciated that access points 26 may be configured tocommunicate using any of a variety of different wireless transmissiontechnologies depending on the application, environment, governmentalregulations, etc. In the exemplary implementation, the access points areconfigured to communicate with the patient monitors (described in moredetail below) as well as other devices under the IEEE 802.11 standardusing Frequency Hopping Spread Spectrum (FHSS) technology in the 2.4 GHzISM (Industrial, Scientific, and Medical) band. The IEEE 802.11communications standard is well known to those of skill in the art.Access points 26 essentially act as network bridges between the wirelesscomponents of network 30 and wired network physical data transportstructure 32. Other wireless transmission, or communication,technologies known to those skilled in the art may be used includingIEEE 802.11a , IEEE 802.11b , and IEEE 802.15.

Exemplary access points 26 may be any wireless transceivers adapted tocommunicate using the IEEE 802.11 FHSS technology. One example of asuitable access point is the SPECTRUM24 AP 3021 available from SymbolTechnologies of Holtsville, N.Y. In other implementations andembodiments, access points 26 may be selected which are configured tocommunicate using other technologies. In any event, the access pointsusually are configured to simultaneously communicate with a plurality ofpatient monitors and/or other wireless devices. For example, the AP 3021access points are adapted to simultaneously communicate with up toapproximately 15 patient monitors.

Each access point typically has a range within which it can communicatewith wireless devices. The range will vary depending on the power of thewireless transmitter, environmental conditions, etc. Typically, theaccess points are arranged within the hospital so that at least oneaccess point is able to communicate with a patient monitor at any pointwithin a defined region of the hospital. For example, if it is desiredthat wireless patient monitors be used on a particular floor of thehospital, then sufficient access points are provided and positioned sothat every location on the particular floor is within the range of oneor more access points. This ensures that a patient associated with apatient monitor can move about the hospital floor without loss ofcentral monitoring. It will be understood that the access points may bearranged to provide wireless coverage within a defined region that isless than an entire floor of the hospital. Alternatively, the accesspoints may be arranged to provide coverage for regions that spanmultiple floors (whether or not adjacent) and/or multiple buildings.

As will be discussed in more detail below, patient monitors and otherwireless devices communicate over physical data transport structure 32by first associating with an access point. Once a patient monitor hasassociated with a particular access point, communications between thepatient monitor and components on physical data transport structure 32are conveyed by the particular access point. However, as the patientmonitor moves out of range of the particular access point and into therange of another access point, the patient monitor associates with theother access point and subsequent communications between the patientmonitor and components on physical data transport structure 32 areconveyed by the other access point.

Use of FHSS technology allows access points to be positioned so that theranges of the access points overlap. Such an arrangement provides forgeographic redundancy in the event an access point fails. In addition,overlapping the access point ranges increases the monitoring capacitywithin the defined region or selected portions of the defined region.The access points typically are configured to communicate with oneanother to minimize or prevent interference. The access points may alsobe configured to manage and balance the communication loads experiencedby each access point. In addition, one or more of the central stationsmay be configured to control the access points to balance communicationloads.

It will be appreciated that in many implementations the communication ofpatient information by wireless transmission must be secure andconfidential. These security needs may be met in any of a variety ofways known to those of skill in the art. For example, the 802.11standard provides WEP (Wired Equivalent Privacy) which encrypts thewireless transmissions. In addition, some implementations may utilizeadditional security measures such as end-to-end data encryption, etc.

In the exemplary embodiment, network 30 also includes a router 44 orsimilar device connected to physical data transport structure 32 betweena first portion 46 and a second portion 48 of physical data transportstructure 32. Components connected to the first portion are assigned IPaddresses corresponding to a first subnet, while components connected tothe second portion are assigned IP addresses corresponding to a secondsubnet. First portion 46 is connected to central stations 24, databasesystem 40, terminal server 42 and the other components of network 30which are configured for wired communications via physical datatransport structure 32. Second portion 48 is connected to access points26. Thus, first portion 46 may be seen as a wired portion of network 30,while second portion 48 may be seen as a wireless portion of network 30.Use of router 44 between wired portion 46 and wireless portion 48 allowsthe wireless portion of the network to be isolated from thecommunication traffic on the wired portion of the network.Communications between patient monitors and central stations are passedby router 44 from wired portion 46 to wireless portion 48 and viceversa. However, communications between central stations and/or othercomponents connected to wired portion 46 are not passed to wirelessportion 48. Alternatively, wired portion 46 and wireless portion 48 maybe directly connected to the same subnet, eliminating the need for arouter.

In the exemplary embodiment, network 30 also includes at least oneserver system 50 connected to the wireless portion of the network. Aswill be discussed in more detail below, server system 50 is adapted toassign IP addresses to the patient monitors once the patient monitorsassociate with an access point. Server system 50 may be configured toassign IP addresses according to any suitable protocol such as theDynamic Host Configuration Protocol (DHCP), the Bootstrap Protocol(BOOTP), etc. It will be appreciated that server system 50 is connectedon the wireless portion of physical data transport structure 32 relativeto router 44 to ensure that requests for IP addresses from the patientmonitors are received at server system 50. Alternatively, router 44 maybe configured to convey the requests for IP addresses between thewireless and wired portions, in which case server system 50 may beconnected on the wired portion of the network.

Server system 50 may be a separate computer system adapted to manage andassign IP addresses only, or it may be configured to perform otherfunctions including network management, etc. In alternative embodiments,one of central stations 24 is configured to perform the functions ofserver system 50, thereby alleviating the need for a separate serversystem 50. In such embodiments, the central station which is configuredto assign IP addresses in the alternative embodiment should be connectedto the wireless portion of network 30 unless router 44 is adapted topass requests for an IP address to the wired portion of the network.

Network 30 may also include one or more wireless communication devicesreferred to herein as clinician terminals 52. The wireless clinicianterminals may take any one of a variety of different forms includingPersonal Digital Assistants (PDA's), Internet Protocol (IP) telephones,portable computers, etc. Clinician terminals 52 include wirelesstransceivers (e.g., RF network cards) that are configured to associatewith access points 26. The clinician terminals also include suitablesoftware executable by the terminals to communicate with the centralstations via access points 26. The clinician terminals may also beconfigured to perform a variety of functions such as receiving anddisplaying patient vital signs data from the central station,transmitting control instructions to the central station to control aselected aspect of the central station, transmitting controlinstructions to the central station for forwarding to a patient monitorto control selected aspects of the patient monitor, sending andreceiving textual messages, receiving and acknowledging alarm signals,etc. In the exemplary embodiment, clinician terminals 52 are configuredto function as quasi-central stations, by displaying patient vital signsdata and providing a user-interface operable by the clinician to controlthe patient monitor.

Clinician terminals 52 enable physicians, nurses and others to obtaininformation concerning a patient from any location within the definedregion of network 30, rather than only at the patient's location or at acentral station. Thus, for example, a clinician several floors away froma patient can receive a notification of an alarm at the patient monitorassociated with the patient. Further, the clinician can evaluate thepatient's condition from the vital signs data without going to thepatient's location. The clinician may then take appropriate actiondepending on the patient's condition. It will be appreciated thatclinician terminals 52 enable clinicians to work more efficiently andeffectively, and to care for a larger number of patients than wouldotherwise be possible. Furthermore, while the clinician terminals mayinclude paging functions, the clinician terminals provide substantiallymore information to the clinicians than pagers.

Exemplary telemetry network 30 also is connected to the main computernetwork 54 of the hospital, referred to hereinafter as the secondary ornon-telemetry network. Secondary network 54 typically includes aplurality of computer terminals 56, database systems 58, etc. Thesecondary network interconnects the hospital's administrative computersand other non-telemetry components. Typically, secondary network 54 isconnected to telemetry network 30 through router 44. This isolates thetelemetry network from non-telemetry communication traffic, whileallowing devices connected to the non-telemetry network to accesspatient vital signs data. Similarly, users of central stations 24 areable to access information on the secondary network as needed. In someimplementations it may be desirable to provide security measures toensure that only authorized users of secondary network 54 are able toaccess telemetry network 30. Any of a variety of suitable securitymeasures may be employed as are known to those of skill in the art.

Network 30 may also be connected to a communications network external tothe hospital such as an extranet, virtual private network, Wide AreaNetwork (WAN), etc. In the exemplary implementation, network 30 isconnected to the Internet 60. Typically, network 30 is connected to theInternet via a firewall 62 or other suitable security device to restrictaccess to patient data and other confidential information.

As shown in FIG. 4, the telemetry network of one hospital 64 may beconnected to the telemetry network and/or the secondary network of oneor more other hospitals 66 in remote locations. The telemetry networkmay be connected to the remote hospitals via Internet 60 or via adirect, non-public network 68 such as is known to those of skill in theart. Central stations 24 of hospital 64 may be configured to transmitpatient information including vital signs data to central stations orother computers in remote hospital 66. Similarly, the central stationsof hospital 64 may be configured to request and receive patientinformation including vital signs data from remote hospitals 66. It willbe appreciated that communication of patient information between remotehospitals allows clinicians to participate in consultations with theirremote colleagues more effectively and efficiently.

In the implementation described above, access points 26 were arrangedwithin the hospital to provide wireless monitoring in a defined regionof the hospital. In alternative implementations, the defined region mayextend outside the hospital. For example, system 20 may include one ormore access points 26 which are positioned outside of the hospital, asshown in FIG. 4. The access points are connected to Internet 60 andconfigured to transmit the patient vital signs data to network 30 andone or more central stations 24. This allows patients to move outside ofthe hospital without loss of continuous central monitoring. So long asthe patient remains within the range of at least one access point, thepatient's vital signs data may be displayed on a central station as ifthe patient was still in the hospital. Similarly, emergency responseworkers could connect a patient monitor to an accident victim so thatthe hospital can monitor the victim's condition while the victim istransported to the hospital.

It will be appreciated that placement of access points outside of thehospital also allows clinicians to access patient data when outside thehospital. As shown in FIG. 4, one or more clinician terminals 52 mayassociate with the external access points to view patient informationand control the patient monitor connected to a patient. This providesclinicians with more flexibility to leave the hospital while continuingto monitor their patients at the hospital (or patients outside thehospital). Alternatively, clinicians may monitor patients using personalcomputers 70 or similar devices configured to connect to Internet 60 andcommunicate with central stations at the hospital. Computers 70 may belocated anywhere a connection is available that provides a communicationchannel using any communication technology. For example, computers 70may be located anywhere a connection to the Internet is available.Alternatively, computers 70 may be configured to associate with anexternal access point and communicate via wireless transmissions.

As discussed above, the defined region of monitoring will extend outsidethe hospital wherever access points 26 are positioned. In areas wherethe external network of access points is undeveloped, patient monitors22 and/or clinician terminals 52 may be configured to communicate usingother wireless communication technologies. For example, theimplementation depicted in FIG. 4 includes a Cellular Digital PacketData (CDPD) network 72, such as is currently used for cellular telephoneand other communications. Patient monitors 22 and/or clinician terminals52 may be configured to communicate with central stations in hospital 64via CDPD network 72. Thus, for example, a patient might be discharged togo home while continuing to be monitored. It will be appreciated thatthis alleviates the need to have new wireless networks installedthroughout a geographic region, since the components of system 20 areconfigured to communicate using preexisting networks. An alternateimplementation (undepicted) would be to use what is known as a GlobalSystem Mobile (GSM), or any other available wide-reaching communicationsystem.

Considering patient monitors 22 in more detail, it will be appreciatedthat there are a variety of different patient monitors available andsuitable for use with system 20. System 20 may include one or morepatient monitors of a single type, or may include multiple types ofpatient monitors, each configured to communicate with one or morecentral stations. For example, the exemplary embodiment of system 20depicted in FIGS. 1 and 2 includes a first type of patient monitor 22 aadapted to be carried or worn by a patient, and a second type of patientmonitor 22 b adapted to be mounted on a bed, wheelchair, etc, as well asbeing carried. Patient monitors 22 a and 22 b may be configured toperform the same monitoring functions or may be configured to performdifferent monitoring functions. In any event, each type of patientmonitor 22 is configured to collect vital signs data from a patient andcommunicate at least a portion of the vital signs data to a centralstation via physical data transport structure 32. Suitable patientmonitors are available from several manufacturers, including theMICROPAQ and PROPAQ patient monitors available from Welch AllynProtocol, Inc. of Beaverton, Oreg.

Turning attention now to FIG. 5, exemplary patient monitor 22 a is shownin more detail. The monitor includes a portable housing 80 having one ormore sensor input ports 82. The housing is sized to be held by aclinician or patient, or to be worn by the patient using a strap, belt,or similar device. Sensor input ports 82 are adapted to receive andconnect to sensor cables 83. Each cable 83 is attached to one or moresensor assemblies (not shown). The sensor assemblies may include anyvital signs sensor assembly adapted to detect and/or measure selectedvital signs data from a patient and transmit the vital signs data viacables 83. Examples, of suitable sensor assemblies includeelectrocardiogram (ECG) sensor assemblies, non-invasive blood pressuresensor assemblies, invasive blood pressure sensor assemblies,temperature sensor assemblies, pulse oximetry sensor assemblies,respiration sensor assemblies, carbon dioxide sensor assemblies, etc.Suitable sensor assemblies are available from Welch Allyn Protocol, Inc.of Beaverton, Oreg. In any event, each sensor input port is adapted toreceive patient vital signs data from the sensor assembly attachedthereto.

Patient monitor 22 a also includes a display device such as displayscreen 84 adapted to display the vital signs data or an imagerepresentative of the vital signs data. Exemplary display screen 84 isin the form of a liquid crystal display (LCD) device. Alternatively oradditionally to display screen 84, patient monitor 22 a may include anyother suitable display device such as a printer, one or more indicatorlights, light-emitting diodes, etc. The patient monitor also includesone or more input devices such as buttons 86 disposed on housing 80.Buttons 86 are operable by a user to input information into patientmonitor 22 a, as will be discussed in more detail below. In addition to,or in place of buttons 86, the patient monitor may include other typesof input devices including switches, knobs, etc. As a furtheralternative, display screen 84 may be a touch-screen adapted to inputinformation in response to contact by the user at selected locations onthe screen. While the exemplary embodiment will be described below ashaving input devices in the form of buttons, it will be understood thatany type of input device may be used.

Exemplary patient monitor 22 a further includes a battery assembly 88having one or more batteries. Battery assembly 88 is mountable in abattery compartment within housing 80. The batteries typically arerechargeable, however non-rechargeable batteries may also be used.Although not shown in FIG. 5, patient monitor 22 a also includes acontroller, a memory device, and an on-board wireless transceiver, alloperably disposed within portable housing 80. An internal antenna 90 ismounted within the housing and coupled to the wireless transceiver.Alternatively, antenna 90 may be disposed externally to housing 80. Anaudio input/output device 92, (e.g., speaker, microphone, buzzer, siren,etc.) is also disposed within the housing and adapted to produce anaudible notification to a clinician, patient, or other user of themonitor. An alternative to the input/output device would be abi-directional audio device.

As shown in FIG. 6, exemplary patient monitor 22 b includes a portablehousing 94 adapted to attach to a bed, wheelchair or other supportstructure. Housing 94 includes one or more sensor input ports 82 adaptedto connect to sensor cables 83 and receive vital signs data from one ormore sensor assemblies (not shown). Similar to patient monitor 22 a,patient monitor 22 b includes a display device such as display screen 84and one or more input devices such as buttons 86. Although not shown inFIG. 6, patient monitor 22 b also includes a battery assembly 88, anantenna 90, and an audio output device 92. As will be described in moredetail below, patient monitor 22 b also includes a controller, a memorydevice and an on-board wireless transceiver, all operably disposed inhousing 94.

Unlike patient monitor 22 a, patient monitor 22 b includes an outputport 96 adapted to receive a hard-wired network connection cable 98 suchas an Ethernet, RS-232, modem line, or similar network communicationscable for connection to physical data transport structure 32 or terminalserver 42. Thus, patient monitor 22 b is configured to communicate withcentral stations 24 using either wireless communications via itson-board wireless transceiver, or wire communications via output port96. As will be discussed in more detail below, patient monitor 22 b maybe configured to automatically switch between wire and wirelesscommunications in various situations.

As mentioned above, each patient monitor 22 includes a controllerdisposed within the portable housing. It will be appreciated that any ofa variety of different computer controllers, micro-controllers, orprocessors, such as are known to those of skill in the art, may be used.The controller, indicated at 100 in FIG. 7, is operably coupled toreceive power from battery assembly 88. The controller may also beconfigured to receive power from other sources (e.g., AC line currentthrough a wall socket, DC current through photovoltaic cells, etc.).

Controller 100 is also connected to memory device 102. It will beappreciated that memory device 102 may be any one or a combination ofdevices adapted to store electronic information such as RAM, ROM, PROM,EPROM, etc. Memory device 102 may also include removable storage mediasuch as magnetic discs and tapes, optical discs, etc. In addition tostoring patient vital signs data, memory device 102 may be configured tostore one or more software control programs executable by controller 100to perform its various functions including receiving and analyzing vitalsigns data, presenting information to a user, etc. In addition, thesoftware will include the necessary programs for communicating withcentral stations 24 (e.g., TCP/IP, DHCP, etc.) While memory device 102has been depicted as a single device, those of skill in the art willappreciate that memory device 102 may be a plurality of either similaror different memory devices.

Controller 100 is also coupled to sensor ports 82 and configured toreceive vital signs data from the sensor assemblies via the sensorports. In addition, controller 100 may be configured to supply powerand/or suitable drive signals onto one or more of the sensor ports todrive the sensor assemblies attached to the ports. In any event, vitalsigns data received at controller 100 may be stored in memory device102, processed, discarded, and/or communicated immediately to a centralstation.

The controller is connected to control wireless transceiver 104 andcommunicate with central stations 24 via the transceiver. Wirelesstransceiver 104 may be any of a variety of wireless transceivers whichare known to those of skill in the art. One example of a suitablewireless transceiver is the SPECTRUM24 LA 3021 PC card, available fromSymbol Technologies of Holtsville, N.Y. Alternatively, other wirelesstransceivers may be used. In any event, wireless transceiver 104 isconfigured to communicate with access points 26 using the appropriatecommunications protocol of network 30. The wireless transceiver isconnected to antenna 90 and transmits data received from controller 100to access points 26. Similarly, the wireless transceiver receivestransmissions from one or more access points and forwards thecommunications to the controller. The wireless communications betweenpatient monitor 22 and the central stations will be discussed in moredetail below.

In the case of patient monitor 22 b, controller 100 is also connected tooutput port 96 and configured to communicate with central stations 24via the output port rather than via wireless transceiver 104. Controller100 may also include a network card or similar device (not shown)adapted to transmit and receive communications via output port 96. Forclarity, the description below assumes that patient monitor 22communicates with central stations 24 via wireless transceiver 104.However, it will be understood that, unless stated otherwise, and forpurposes of this description, communications via output port 96 areviewed as identical to communications via the wireless transceiver, andtherefore both types of communications are included within thedescription. A distinction between wireless and hard-wired communicationis that patient location (room) is known with hard-wired communication(via the network jack to which the monitor is connected) and not knownwith wireless communication. However, for purposes of this description,that distinction is not seen as pertinent and that is why communicationsvia output port 96 are viewed as identical to communications via thewireless transceiver.

Controller 100 is also connected to receive inputs from buttons 86. Thebuttons are operable by a user of the patient monitor to inputinformation to the controller, as well as to control the controller.Each button may have a single function or may have a variety offunctions depending on such factors as the operating condition of thecontroller, status of the sensor assemblies, communications with acentral station, screen displays, etc. In the exemplary embodiment,controller 100 is configured to control the function of buttons 86 andto disable the buttons under defined conditions. Controller 100 isconfigured to control display screen 84 to display an image representingthe vital signs data. It will be appreciated that the image displayed ondisplay screen 84 will vary depending on the vital signs data collectedby the patient monitor. Additionally, exemplary controller 100 isconfigured to change the display based on instructions received from theuser via buttons 86. For example, the user might select betweendisplaying a single ECG signal from a single electrode, or multiple ECGsignals from multiple electrodes. FIG. 8 shows an exemplary displayscreen 84 on which vital signs data is being displayed. A waveformregion 106 of the display shows an image representing the signal datareceived from an ECG sensor assembly. A numeric region 108 of thedisplay shows images that provide numerical representations of the vitalsigns data (e.g., heart rate, oxygen saturation in the patient's blood,etc.). The display may also include a patient identifier 110 thatuniquely identifies the patient, such as the patient's name, etc. FIG. 9shows another exemplary display screen 84 similar to the one in FIG. 8.However, the display screen shown in FIG. 9 has been changed to includea message region 112 for displaying messages to a user. Similarly, FIG.10 shows another exemplary display screen 84 in which the image has beenchanged to include a user-interface region 114. The user-interfaceregion allows a user to enter information and control the patientmonitor by operating buttons 86. Control of the display screen will bedescribed in further detail below.

Controller 100 is also connected to control audio output device 92and/or other audible indicator devices to produce audible messages orsignals. The controller may be configured to control the audio outputdevice to produce audible signals under any one or more of a variety ofconditions. For example, controller 100 is typically configured toanalyze at least some of the vital signs data and produce an audiblealarm if the vital signs data is outside a selected nominal range. Theanalysis of vital signs data and detection of alarm conditions will bedescribed in further detail below.

While one exemplary functional embodiment of patient monitors 22 hasbeen depicted in FIG. 7 and described above, it will be appreciated thatmany other configurations are possible. Thus, the invention is notlimited to the exemplary embodiment described, but includes any patientmonitor configuration adapted to collect vital signs data from a patientand communicate the vital signs data to one or more central stations.

Typically, patient monitors 22 are configured to function as stand-alonedevices capable of providing local patient monitoring regardless ofwhether the patient monitor is in communication with a central station.The patient monitor may be configured to begin monitoring immediatelyupon power-up and attachment of at least one sensor assembly.Alternatively, the patient monitor may be configured to begin monitoringupon receipt of an actuation signal.

Patient monitors 22 are also configured to attempt to establishcommunications with one or more central stations and communicate thevital signs data to the central stations. In the exemplary embodiment,the patient monitors are configured to attempt to establishcommunications immediately at power-up and to continue the attempt untilcommunications are established. Alternatively, one or more of thepatient monitors may be configured to attempt to establishcommunications only in response to an instruction by a user and/or theoccurrence of selected conditions. Those of skill in the art willappreciate that the process of establishing communications with one ormore central stations, also referred to herein as the rendezvousprocess, may be carried out in any of a variety of different ways. Inaddition, the rendezvous process may vary depending on whether thepatient monitor is communicating through wireless or wirecommunications, as well as on whether the patient monitor isestablishing a new communications connection or reestablishing priorcommunications which were lost or terminated.

The rendezvous process of the exemplary embodiment is schematicallyillustrated in FIG. 11. The process begins with establishing aconnection to physical data transport structure 32 by any one of severalmethods. Where patient monitor 22 is configured to communicate usingonly wireless communications, the patient monitor establishes aconnection to physical data transport structure 32 by associating withan access point, as indicated at 200. It will be appreciated that theprocess of associating with an access point may vary with varyingconfigurations of the access point and/or varying configurations of thepatient monitor. In the exemplary embodiment, wireless transceiver 104associates with a patient monitor according to the IEEE 802.11 standard,and the details of that standard are known to those skilled in the art.Certain features of the exemplary embodiment include that (i) thepatient monitors can be used in any telemetry network described herein(such as the 802.11-standard telemetry network) without user-adjustmentof the communications frequency, and (ii) the patient monitorsautomatically scan for access points and detect access-pointconfiguration and synchronization information.

In addition, the wireless transceiver determines which access points arewithin range of the patient monitor, and the current communications loadon the in-range access points. Using this information, the patientmonitor selects one of the in-range access points with which tocommunicate, and begins the authentication process which is followed bythe association process. Once the authentication and associationprocesses are complete, the connection between the patient monitor andphysical data transport structure 32 is established.

In the exemplary embodiment where communications over network 30 conformto the IP protocol, each device must have an associated IP address withwhich to send and receive communications. In some embodiments, patientmonitor 22 may have a permanently assigned IP address stored in memorydevice 102. Alternatively, patient monitor 22 may not have an assignedIP address, and instead may be configured to request an IP address uponestablishing a connection with physical data transport structure 32, asindicated at 202 and 204. Typically, patient monitor 22 requests an IPaddress by transmitting a broadcast request to server 50 using theappropriate protocol (e.g., DHCP, BOOTP, etc.). The request is answeredby server 50, which responds by assigning the patient monitor an IPaddress from a store of available IP addresses, and then transmitting anotification of the assignment to the patient monitor. Alternatively,server 50 may store a pre-assigned IP address for each device, andrespond with the corresponding pre-assigned IP address. Upon receivingthe assigned IP address, the patient monitor is prepared to broadcast arequest for communications to one or more central stations, as will bedescribed in more detail below.

Where patient monitor 22 is adapted to communicate using either wirelessor wire communications, the process for establishing a connection tophysical data transport structure 32 will vary depending on whether awireless or wire connection is established. In the former case, theprocess may occur as described above, i.e., first associating with anaccess point, and then requesting an IP address if necessary.Alternatively, if a wire connection is to be established, the patientmonitor may be physically connected to a terminal server which isconnected to the network, as indicated at 206. It will be appreciatedthat the connection indicated at 206 may alternatively take other forms,such as a modem connection to a modem server, etc. In any case, once theconnection is established and any necessary hand-shaking between thepatient monitor and the terminal server is completed, the patientmonitor is prepared to broadcast a request for communications to one ormore central stations. Patient monitor 22 will communicate using the IPaddress of the server, and therefore is not required to have its own IPaddress.

As a further alternative, the patient monitor may be directly connectedto a hard-wired connection on physical data transport structure 32 withan Ethernet or similar connection technology, as indicated at 208. Aswith a patient monitor that is connected to communicate using wirelesscommunications, a patient monitor directly connected to physical datatransport structure 32 may have a permanently assigned IP address, ormay request the assignment of an IP address once the physical connectionis established. In any event, in the hard-wired implementation, theterminal server is then prepared to initiate a request forcommunications to one or more central stations.

Regardless of how a patient monitor establishes a connection withphysical data transport structure 32, the patient monitor must thenestablish communications with a central station by broadcasting arequest for communications to the central station, as indicated at 210.It will be appreciated by those of skill in the art that a patientmonitor may broadcast a request for communications in any of a varietyof ways. In the exemplary embodiment, the patient monitor transmits therequest as a UDP broadcast to all central stations. Alternatively, othercommunication protocols may be used.

The UDP communications request may include a variety of parametersadapted to inform the central station about the patient monitor. Forexample, communications requests typically include such information asthe identity, type, and/or capabilities of the patient monitor, the IPand MAC (Media Access Control) addresses of the patient monitor, theversion of software installed on the patient monitor, etc. The requestmay also include an indicator of the type of communications desired. Forexample, the patient monitor may request communications to establishcentral monitoring of a patient, download newer versions of the patientmonitoring software (discussed in more detail below), or perform networkmaintenance, etc. This information allows the central station todetermine how to respond to the request. Unless stated otherwise, thedescription below will assume that the patient monitor's communicationsrequest is for the purposes of establishing centralized monitoring of apatient.

In the exemplary embodiment, the communications request is passed to,and received by, all central stations of network 30, as indicated at212. Any routers or other network devices connected to physical datatransport structure 32 are configured to pass on the request to thecentral stations as necessary. Alternatively, the request may beconveyed to fewer than all of the central stations, or to a singlecentral station. Each central station is configured to respond to thecommunications request when received. Upon receiving the first responsethe patient monitor transmits an acknowledgement to the central stationthat sent the first response. The patient monitor is configured toreject subsequent responses by transmitting a “reject” message to anycentral station that sends a subsequent response. The central stationsare configured to cease sending responses to the communications requestafter receiving a “reject” message, unless a new request forcommunications is received.

In some embodiments, the central stations may be configured to ensurethat a preferred central station responds to the communications request.For example, the central stations may be configured to recognize apatient monitor that has communicated with network 30 in the past (e.g.,based upon information transmitted in the communications request), andto allow the particular central station that was previously incommunication with the patient monitor to respond first. Thus, in theexemplary embodiment the central stations are configured to determine ifa communications request was sent by a patient monitor which waspreviously in communication with a particular central station within apredefined time period. If so, the particular central station isconfigured to respond to the request immediately, while the remainingcentral stations will wait for a relatively short period of time (e.g.,10, 15, 20, 25, or 30 seconds, etc.) before responding. This priority isbased on the assumption that the patient monitor is likely stillconnected to the same patient as during the previous communications, andthat the patient is likely to be monitored at the same central stationas during the previous communications. In any event, once the patientmonitor receives a first response to its communications request, thepatient monitor and the central station which sent the first response(hereinafter referred to as the “provisional central station”) begincommunicating to configure the centralized monitoring session, asindicated at 214.

As will be described in more detail below, the particular centralstation which serves as the provisional central station begins theprocess of configuring the monitoring session. However, before thecentralized monitoring begins, one of the central stations of network 30is selected to complete the configuration process and perform thecentral monitoring. This selected central station is referred to hereinas the “primary central station.” If the provisional central station isselected to be the primary central station, then no change incommunications is needed, and the provisional central station assumesthe role of the primary central station. Conversely, if a differentcentral station is selected to be the primary central station,communications with the patient monitor are transferred from theprovisional central station to the selected central station, which thenassumes the role of primary central station.

As is known to those of skill in the art, wireless communications whichhave been established between a patient monitor and a primary centralstation may be lost or “dropped” for any of a variety of reasons. Forexample, the wireless transmissions may not be received by the accesspoint and/or the wireless transceiver of the patient monitor because thepatient monitor is moved out of the defined range of network 30 (i.e.,out of range of any access point). Similarly, the transmissions may havebeen blocked by structures between the patient monitor and the accesspoint, such as when the patient monitor is taken into an elevator orsimilar enclosure. Alternatively, a portion or device of network 30 mayhave failed, causing the communications to be dropped. As a furtheralternative, the battery in the patient monitor may have been replacedor discharged, causing the patient monitor to lose communications.

The response by patient monitor 22 and central stations 24 tocommunications dropouts may vary depending on the length and/or cause ofthe dropout. In the exemplary embodiment for example, a relatively briefdropout (e.g., less than approximately 10, 20, or 30 seconds, etc.), istreated as an interruption rather than as an actual loss ofcommunications. Lost or incomplete transmissions due to suchinterruptions may be resent, discarded, or ignored according to thecommunications protocols used by the patient monitor and centralstations. Once the interruption ends, the patient monitor and primarycentral station resume communicating as before.

In the event of a loss of communications that extends beyond a briefinterruption, exemplary patient monitor 22 is configured to detect theloss and automatically attempt to restore the communications. If thepatient monitor is no longer associated with an access point, thepatient monitor attempts to establish an association as described in the802.11 standard, and continues to attempt to establish an associationuntil association with an access point is regained. Once the patientmonitor re-associates with an access point (or if the patient monitornever lost the association), the patient monitor broadcasts a requestfor communications to the central stations, and the rendezvous processproceeds as described above. Once the patient monitor is incommunication with a provisional central station, the patient monitorand provisional central station begin the process of configuring themonitoring session, as indicated at 214.

It will be appreciated that the session configuration process mayproceed in any of a variety of different ways to configure a variety ofdifferent monitoring parameters. For example, the configuration processmay identify which patient is being monitored, which central stationwill monitor the patient, which central station will control the patientmonitor, what types of vital signs data should be monitored, how thevital signs data should be analyzed, what alarm conditions should bedetected, how the patient monitor should function, etc. An exemplarysession configuration process is indicated generally at 216 in FIG. 12.During process 216 a primary central station is selected, the monitoredpatient is identified, and the patient's room or other location isspecified.

Referring to FIG. 12, the provisional central station first determineswhether the patient monitor is still connected to the same patient asbefore the communications dropout. If such is the case, then theprovisional central station assumes that the patient monitor isattempting to restore communications which were lost, and prior valuesfor patient identity, etc., may be used. Alternatively, if the requestis to establish new communications, then the central station determinesthe information needed to complete the configuration by querying a userof the patient monitor, as will be described in more detail below.

The provisional central station may be configured to employ a variety ofdifferent methods or mechanisms to determine whether the patient monitoris still connected to the same patient. In the exemplary embodiment forexample, the provisional central station first sends a request to thepatient monitor for an indication of whether the patient monitor wascontinuously monitoring the patient during the period the communicationswere lost, as indicated at 218. If the patient monitor respondsaffirmatively, then the patient currently being monitored is necessarilythe same patient that was previously monitored.

Patient monitor 22 is configured to receive the request and detectwhether it continuously monitored the same patient during thecommunication dropout. Typically, the patient monitor is configured todetect continuous monitoring by detecting whether the patient monitorwas operational during the communications dropout, and whether vitalsigns data was continuously received via at least one of the sensorassemblies. For example, one exemplary ECG sensor assembly connectableto a patient is adapted to continuously send ECG vital signs data topatient monitor controller 100. If the patient monitor is disconnectedfrom the patient during the dropout, the ECG signal will lapse. Anylapse in the ECG vital signs data is detected by the controller.Alternatively, the ECG sensor assembly, or other types of sensorassemblies, may be configured to detect actual contact with the patient.In any event, the patient monitor responds to the request by informingthe provisional central station of whether the patient monitor hascontinuously monitored the same patient. It should be noted that thepatient monitor may be monitoring the patient through sensor assembliesthat do not continuously send vital signs data to the controller, andthat do not detect contact with the patient. In which case, the patientmonitor will be unable to confirm that it has continuously monitored thesame patient, and will respond to the request from the central stationaccordingly.

If, at step 218, the patient monitor responds that it has continuouslymonitored the same patient, the provisional central station proceeds toperform a reconnect process, as indicated at 220 and as described below.Alternatively, if the patient monitor responds that it has notcontinuously monitored the same patient, the provisional central stationthen determines whether the patient monitor was recently connected tonetwork 30, as indicated at 222. In other words, if the time periodduring which communications between the patient monitor and the primarycentral station were lost is less than a predetermined length of time,then the provisional central station concludes that the patient monitoris attempting to restore a recent connection, and proceeds to performreconnect process 220. Otherwise, the provisional monitor concludes thatthe patient monitor is attempting to establish a new communicationssession. It should be noted that if the patient monitor was continuouslymonitoring the same patient during the communications dropout, then theprovisional central station may safely assume the patient monitor isstill connected to the same patient regardless of the length of thedropout.

The predetermined length of time that defines a recent connection may beset to any desired length of time as appropriate for a particularapplication. In the exemplary embodiment, the predetermined length oftime is selected to be less than the minimum time period (e.g., 1, 2, 3,4, or 5 minutes, etc.) normally needed to disconnect a patient monitorfrom one patient and reconnect the patient monitor to another patient.Thus, if the patient monitor was out of communication for any period oftime less than that minimum disconnection/reconnection time, theprovisional central station concludes that the patient monitor is stillconnected to the same patient. Alternatively, other time periods may beused.

The provisional central station may determine whether the patientmonitor was recently connected in various ways. Typically, each centralstation is adapted to store patient vital signs data in database system40. The vital signs data includes the time of collection by the patientmonitor and/or receipt by the central station. Thus, the provisionalcentral station may be configured to access database system 40 todetermine the time that the last vital signs data was received from thepatient monitor. Alternatively, the patient monitor may be configured todetermine the length of the dropout and to inform the provisionalcentral station, either automatically or in response to a query from theprovisional central station.

In addition to the length of time during which communications were lost,the provisional central station may be configured also to evaluate otherconditions at step 222. For example, if the prior communications weredropped intentionally, i.e., in response to a command by a user, theprovisional central station may be configured to assume that a newpatient has been connected to the patient monitor. In which case, thepatient monitor is not attempting to restore a recent connection, butinstead is attempting to establish a new communications connection.

As mentioned above, the provisional central station proceeds to performa reconnect process, indicated at 220, if the provisional centralstation determines either that the patient monitor continuouslymonitored the same patient during the dropout, or that the patientmonitor was recently connected to communicate with a primary centralstation. During reconnect process 220 the provisional central stationautomatically determines which patient is being monitored by the patientmonitor, and which central station served as the primary central stationbefore the communications dropout. Typically, this information is storedby the patient monitor in memory device 102, and is communicated to theprovisional central station by the patient monitor. Alternatively, theinformation may be stored in database system 40 and read by theprovisional central station via physical data transport structure 32.

In any event, if the provisional central station is not the primarycentral station, then the provisional central station conveys a messageto the primary central station to take over the remainder of therendezvous process. If the primary central station is available, itbegins communicating with the patient monitor via physical datatransport structure 32 and conducts the remainder of the configurationprocess as described below. Likewise, the patient monitor transmits allsubsequent communications to the primary central station, and theprovisional central station ends further communications with the patientmonitor.

Alternatively, if the primary central station does not respond to theprovisional central station or is otherwise unavailable, the provisionalcentral station may be configured to transmit a message to the patientmonitor that the primary central station is unavailable. In theexemplary embodiment, the patient monitor controller causes displayscreen 84 to display a user-interface 114, such as shown in FIG. 13,including a message that the primary central station is unavailable. Theuser-interface may also include instruction elements 116 which areselectable by a user to instruct the central station to recheck theavailability of the primary central station, or to try a new primarycentral station. The clinician or other user of the patient monitor mayuse buttons 86 to select the desired instruction, which the patientmonitor then communicates to the provisional central station. Dependingon the user's instructions, the provisional central station either sendsanother message to the primary central station to take over thecommunications, or transmits a list of central stations to the patientmonitor. In the latter case, controller 100 causes the display device todisplay a list of central stations, from which the user may select usingbuttons 86. The patient monitor transmits the user's selection to theprovisional central station, which sends a message to the selectedcentral station to take over the communications. If the selected centralstation is not available, the provisional central station informs thepatient monitor and the user either selects a different central station,or instructs the provisional central station to retry the selectedcentral station. This process may be repeated until an available centralstation is selected to act as the primary central station. The selectedcentral station then begins communicating with the patient monitor andconducts the remainder of the configuration process.

Once the primary central station takes over the communications with thepatient monitor, the primary central station is configured to determinethe patient identity (patient ID) of the particular patient beingmonitored by the patient monitor. The primary central station determinesthe patient ID by transmitting a request for the patient ID to thepatient monitor. If the patient monitor cannot provide the patient ID,the primary central station then accesses database system 40 to obtainthe patient ID which was stored during the patient monitor's lastcommunication session. Once the primary central station determines theidentification of the particular patient being monitored by the patientmonitor, the primary central station thereafter associates all vitalsigns data received from the patient monitor with the particularpatient. In addition, the vital signs data along with other patientinformation may be stored on database system 40, and then retrieved forviewing and analysis at a later time.

After the primary central station has assumed the communications withthe patient monitor and determined the identity of the patient beingmonitored, the primary central station then determines whether thepatient has been assigned to a particular location, such as a roomnumber, bed, ward, floor, etc., as indicated at 224 in FIG. 12. Thisinformation may then be displayed on central station monitor 36 toinform the clinician of the patient's assigned location. However, inview of the portability of patient monitors 22, a particular patient maybe temporarily absent from his or her assigned location even though thepatient is continuously monitored at the central station. In any event,the primary central station determines whether the patient has beenassigned to a particular location by sending a request for theinformation to the patient monitor. If the patient monitor is unable toprovide an assigned location, the primary central station may beconfigured to search database system 40 for the information.

If the primary central station is unable to determine the assignedlocation, the central station is configured to query the user of thepatient monitor for the patient's assigned location, as will bedescribed in more detail below. Otherwise, the rendezvous andconfiguration processes are complete, and the primary central stationproceeds to confirm that no other patient monitor is monitoring the samepatient, as indicated at 226. In addition to checking the other patientmonitors in communication with the primary central station, the primarycentral station also communicates with other central stations in network30 to ensure that the same patient is not being monitored by a differentcentral station. In the event the primary central station determinesthat another patient monitor is monitoring the same patient, an alarm orother indication may be displayed at the primary central station and/orthe patient monitor so that a different patient ID may be selected.

As described above, the patient monitor is adapted to automaticallyattempt to restore communications with its primary central station inthe event the communications are lost. Upon reestablishingcommunication, the primary central station (or a provisional centralstation, if different than the primary central station) is configured toautomatically determine whether the patient monitor is still connectedto the same patient. The central station may use a variety of mechanismsand methods to determine whether the patient monitor is still connectedto the same patient, including measuring the length of time of thecommunications dropout, and determining whether the patient monitordisconnected from the patient data during the dropout. If the patientmonitor is still connected to the same patient, the central station thenassociates the patient monitor with the patient so that any vital signsdata received from the patient monitor is also associated with thepatient. It will be appreciated that the capability to automaticallyidentify the monitored patient at the central station after acommunications dropout, enables the central station to monitor a largenumber of patients without constant intervention by a clinician toreconfigure a patient monitor each time a dropout occurs. Furthermore,the automatic configuration ensures that centralized monitoring of thepatient resumes as soon as the patient monitor restores communicationwith the central station.

Turning attention back to FIG. 12, if the provisional central stationdetermines that the patient monitor is not attempting to restore lostcommunications, the provisional central station proceeds to configure anew monitoring session by determining the identity of the patient beingmonitored, the primary central station which will monitor the patient,and the patient's assigned location. When the patient monitorestablishes a new communications connection with the provisional centralstation, the patient monitor automatically displays a notification to auser of the patient monitor on display screen 84. As will be describedbelow, the notification typically includes a user-interface operable bya user of the patient monitor to configure the communications session.

It will be appreciated that the provisional central station maydetermine the identity of the monitored patient in various ways. Forexample, even where the patient monitor has not recently been incommunication with a central station and has not been monitoring thepatient continuously since its last communication with a centralstation, it nevertheless may be more likely than not that the patientmonitor has been reconnected to monitor the same patient. In theexemplary embodiment therefore, the provisional central station firstdetermines whether the identity of the previous patient monitored by thepatient monitor is available, as indicated at 228.

To determine whether the patient ID of the previous patient isavailable, the provisional central station may be configured first toquery the patient monitor. Exemplary patient monitor 22 is configured tostore the ID of the previous patient in memory device 102, unless thepatient ID is cleared by the user. Thus, the exemplary provisionalcentral station transmits a request to the patient monitor for theprevious patient ID. If the previous patient ID is available at thepatient monitor, the patient monitor communicates the previous patientID to the provisional central station. Otherwise, the patient monitorresponds that no patient ID is available.

If the patient ID is not available at the patient monitor, theprovisional central station may be configured to search database system40 for the previous patient ID associated with the patient monitor.Alternatively, if the patient monitor is connected to physical datatransport structure 32 via a hard-wired connection, the provisionalcentral station may be configured to search the database system for theprevious patient ID associated with the particular location of thehard-wired connection. This strategy is based on the likelihood that thepatient who was previously in the room with the hard-wired connectionhas not been moved since the last communications session. In theexemplary embodiment, the provisional central station is configured tosearch for the patient ID associated with the patient monitor if thepatient monitor is communicating via wireless transmissions, and tosearch for the patient ID associated with the particular location of thehardwired connection if the patient monitor is communicating via wire.

If the previous patient ID is available (either from the patient monitoror the database system), the provisional central station communicates aninstruction to the patient monitor to confirm whether the patientcurrently being monitored is the same as the last patient monitored, asindicated at 230. In response, controller 100 automatically causesdisplay screen 84 to display a user-interface 114, such as illustratedin FIG. 14. The user-interface displays the previous patient's identity(i.e., the patient's name, identifying number, and/or other identifyingdesignation) and asks the user to confirm that the patient monitor isconnected to the previous patient. Exemplary user-interface 114 alsoincludes instruction elements 116 which are selectable by the user toindicate that the patient monitor is or is not connected to the previouspatient. In the exemplary embodiment, the user-interface also displaysthe patient's assigned location, indicated at 118, and the centralstation that previously monitored the patient, indicated at 120. Thus,the clinician or other user is prompted by user-interface 114 to confirmthat the same patient is being monitored, and is assigned to the samelocation, and is to be monitored by the same central station.Alternatively, the user may indicate that a new patient is beingmonitored, or that the patient has been assigned to a new location, orthat the patient should be monitored by a different central station. Theuser's selection is communicated by the patient monitor to theprovisional central station.

As shown in FIG. 12, if the user confirms the previous patient, locationand primary central station (i.e., by selecting the instruction elementlabeled “YES”), the rendezvous and configuration processes are complete,and the primary central station proceeds to confirm that no otherpatient monitor is monitoring the same patient, as indicated at 226 andas discussed above. It should be noted that if the provisional centralstation is not the primary central station, then the provisional centralstation sends a request to the primary central station to take over thecommunications and complete the configuration process, as describedabove.

Alternatively, if the user responds by selecting a different one of theinstruction elements, the provisional central station proceeds todetermine the necessary configuration information. For example, if theuser indicates that the patient currently being monitored is not theprevious patient (i.e., by selecting the instruction element labeled“NO”), the provisional central station determines whether the patientmonitor is configured to display a list of patients, as indicated at232. The provisional central station may determine whether the patientmonitor is configured to display a list of patients in various ways,including by sending a query to the patient monitor for itscapabilities, or by accessing database system 40 to ascertain thecapabilities of the patient monitor based on the type of patientmonitor. As mentioned above, the type of the patient monitor may betransmitted to the provisional central station during the initialportion of the rendezvous process.

If the patient monitor is not configured to display a list of patients,then the patient ID confirmation process is passed to the centralstation, as indicated at 226. The central station typically isconfigured to display a user-interface allowing a clinician to specifythe patient ID and the patient's assigned location. In addition, theclinician may instruct the central station to transfer communicationswith the patient monitor to a different central station, as will bedescribed in more detail below. If, on the other hand, the patientmonitor is configured to display a list of patients, the central stationaccesses database system 40 to identify at least some of the patientsadmitted to the hospital, and transmits a list of those patients to thepatient monitor.

As indicated at 234, exemplary controller 100 displays the list ofpatients on display screen 84. An exemplary display screen presenting alist of patients is illustrated in FIG. 15. Rather than identifying thepatient at the patient monitor, the clinician may operate buttons 86 toinstruct that the patient's ID be selected at the central station, asindicated at 236. In which case the patient ID confirmation process ispassed to the central station, as indicated at 226 and as discussedabove. Alternatively, the clinician may select the ID of themonitored-patient from the patient list. The patient's ID is thencommunicated to the central station by the patient monitor. Next, thecentral station transmits a list of locations to the patient monitorcontroller, which displays the list to the user, as indicated at 238.Once the user selects the patient's assigned location from the list, thecontroller communicates the information to the central station. Finally,the central station confirms the patient is not being monitored by adifferent patient monitor, as indicated at 226, at which point therendezvous and configuration processes are complete.

If, at step 230, the clinician indicates that the patient has beenassigned to a different location (i.e., by selecting the instructionelement labeled “NEW ROOM”), the patient monitor communicates thisinformation to the central station, which responds by sending a list oflocations to the patient monitor, as described above. The clinician thenselects the patient's assigned location from the list, as indicated at238. The location assignment is communicated to the central station,which then completes the rendezvous and configuration processes byconfirming that the patient is not being monitored by a differentpatient monitor.

Returning attention briefly to FIG. 14, if the central station thatmonitored the previous patient will not be the primary central station,the clinician requests communications with a different central station(e.g., by selecting the control element labeled “NEW UNIT”). Theclinician's instruction is then communicated to the provisional centralstation, which responds by transmitting a list of central stations innetwork 30. Controller 100 displays the list of central stations ondisplay screen 84, as indicated at 240 in FIG. 12. FIG. 16 illustratesan exemplary user-interface on display screen 84, including a list ofuser-selectable central stations. Once the clinician selects the desiredcentral station from the list, the selection is communicated to theprovisional central station. If the provisional central station is notthe selected central station, the provisional central station sends arequest to the selected central station to take over the communicationsand configuration process. If the selected central station is available,it takes over the communications with the patient monitor and completesthe configuration process. Otherwise, the provisional central stationcauses the patient monitor to notify the clinician that the selectedcentral station is unavailable, as described above.

Once the a central station is selected to be the primary central stationand assumes the communications with the patient monitor, the primarycentral station proceeds to determine the identity of the patient andthe patient's assigned location. As described above, the identity of thepatient and the patient's assigned location may be entered by theclinician at the patient monitor and then communicated to the primarycentral station. Alternatively, the patient ID and assigned location maybe specified at the primary central station. In any event, once theprimary central station has confirmed the identity and the assignedlocation of the patient, as indicated at 226, the rendezvous andconfiguration processes are complete.

As described above, exemplary configuration process 216 is adapted toautomatically determine the patient's identity, etc., whenever possible.This tends to minimize the amount of effort required by the clinician toconfigure the patient monitor for centralized monitoring. However, itwill be appreciated that the provisional central station may beconfigured also to determine the patient identity, primary centralstation, and assigned location in other ways. For example, if thepatient ID is not available at step 228, then the exemplary provisionalcentral station is configured to determine whether a list of centralstations should be presented to the clinician, as indicated at 232.Typically, a list of central stations is presented whenever network 30includes more than one central station. As indicated at 240 anddescribed above, the provisional central station transmits the list ofcentral stations to the patient monitor for display to the clinician.The clinician selects a desired central station to serve as the primarycentral station. The patient monitor communicates the selection to theprovisional central station, which sends a message to the selectedcentral station to take over the communications. If the selected centralstation is not available, the clinician is informed to make anotherselection, as described above. If, at step 242, the provisional centralstation determines that a list of central stations should not bepresented to the user, the provisional central station becomes theprimary central station and completes the remainder of the configurationprocess.

Once the primary central station is in communication with the patientmonitor, the primary central station queries the clinician for thepatient ID and assigned location. Alternatively, the patient ID andassigned location may be specified at the primary central station. Inany event, the primary central station then confirms that no otherpatient monitors are monitoring the same patient, thereby completing therendezvous and configuration processes.

It will be appreciated by those of skill in the art that the exemplaryrendezvous and configuration processes illustrated in FIGS. 11 and 12and described above, provide a variety of capabilities for monitoringpatients via medical telemetry network 30. For example, a clinician mayselect which central station will monitor the patient by enteringinstructions at the patient monitor. The clinician's instructions arecommunicated to the provisional central station, which then sends arequest to the selected central station to take over the communications.Alternatively, the patient monitor may send a request for communicationsdirectly to the selected central station in response to the clinician'sinstructions. In any event, the clinician is not required to configurethe patient monitor at the central station, but instead may configureand initiate the central monitoring process without leaving thepatient's location.

Furthermore, exemplary patient monitor 22 is configured to automaticallyattempt to establish communications with a central station beginning atpower-up. The patient monitor determines, without user intervention, thecommunications settings needed to establish a connection and tocommunicate with network 30 such as transmission frequency, IPaddresses, synchronization, etc. Thus, a patient monitor may be shippedfrom its manufacturing site to any location in the world and the patientmonitor will automatically configure itself to begin communications witha local medical telemetry network according to the present invention.Similarly, a patient monitor used in a network at one location may betaken to a different location, where the patient monitor will configureitself to communicate with the local medical telemetry network at thedifferent location. As a result, patient monitors 22 may be operatedwithout specialized training or knowledge in network communications.Instead, clinicians may place a new patient monitor in immediate usesimply by powering-up the patient monitor.

If communications between a patient monitor and central station arelost, the patient monitor automatically attempts to restore thecommunications without requiring reconfiguration. However, if thepatient monitor is attempting to establish a new communicationsconnection, the clinician or other user of the patient monitor isautomatically notified once a communications connection (either wire orwireless) is established to allow the monitoring session to beconfigured. A user-interface for configuring the monitoring session isautomatically displayed on the patient monitor display screen. Theuser-interface is at least partially defined by instructions receivedfrom the central station, and is operable by a user of the patientmonitor to identify the monitored patient, and to select a primarycentral station to perform the central monitoring, etc. After a primarycentral station is identified and assumes communications with, andcontrol of, the patient monitor, the patient is continuously monitoredat the primary central station. In view of the capability of the patientmonitors and central stations to automatically initiate and configurethe centralized monitoring process, system 20 represents a substantialadvancement in patient monitoring.

It will be appreciated by those of skill in the art that the rendezvousand configuration processes described above are just one of the manyways in which the central stations and patient monitors may beconfigured to establish new communications and/or restore lostcommunications. Many variations and modifications to the rendezvous andconfiguration processes are possible within the scope of the invention.Therefore, it will be understood that the invention is not limited tothe particular exemplary processes described above, but includes allsuch processes, variations, and modifications suitable for establishingcommunications between a patient monitor and a central monitoringstation via a communications network structure.

Once patient monitor 22 has established (or restored) communicationswith the primary central station, the patient monitor is configured tocontinuously communicate the vital signs data it collects to the centralstation. In the exemplary embodiment, patient monitor 22 is configuredto communicate all vital signs data that is collected. Alternatively,the patient monitor may be configured to communicate only a portion ofthe vital signs data collected. In any event, the central station isconfigured to receive the vital signs data and associate it with thepatient being monitored. As mentioned above, the central stationtypically is configured to communicate simultaneously with a pluralityof patient monitors, in which case the vital signs data received fromeach patient monitor is associated with the particular patient connectedto that patient monitor.

Although patient monitor 22 is adapted to communicate with one or morecentral stations to establish central monitoring, the patient monitor isalso configured to provide patient monitoring at the patient's location.As mentioned above, exemplary controller 100 is adapted to receive thevital signs data via sensor ports 82, and to display an image on displayscreen 84 that represents at least a portion of the vital signs data. Itwill be appreciated that the image may take any of a variety ofdifferent forms which will vary depending on the type of vital signsdata collected. Thus, exemplary patient monitor 22 provides continuouslocal monitoring regardless of whether the patient monitor is incommunication with a central station. Buttons 86 enable a clinician orother user to control a variety of functions including the informationdisplayed on display screen 84, the format of the displayed image, thevital signs data collected, analysis of the vital signs data, alarmconditions, etc. For example, controller 100 may be controllable todisplay signals from selected sensor assemblies such as an ECG sensorassembly, or from a selected electrode of the ECG sensor assembly. Inaddition, the controller may be configured to analyze at least some ofthe collected vital signs data using one or more user-selectableparameters to provide additional information.

Similarly, controller 100 may be configured to analyze the vital signsdata to detect whether the data is within certain defined nominalranges, and to indicate an alarm condition if the controller detectsthat a portion of the data is not within the defined ranges. Forexample, if the upper and lower parameter values for heart rate are 120and 50 beats per minute, respectively, the patient monitor will indicatean alarm if the detected heart rate is either greater than 120 or lessthan 50 beats per minute. Alternatively, any other portion of thecollected vital signs data may be analyzed for alarm conditions, such asblood pressure, temperature, oxygen saturation in the patient's blood(SpO2), etc. Further, the defined nominal ranges typically are variableparameters and selectable by the user to specify particular alarmconditions for a particular patient. FIG. 17 illustrates an exemplaryuser-interface displayable on display screen 84, and operable by aclinician to specify the parameter values used by controller 100 toanalyze the vital signs data. Alarm indications may include warningmessages on display screen 84 and/or warning sounds from audio outputdevice 92, etc.

Patient monitor 22 may also be configured to detect equipment orcommunications problems and provide an indication of the problem to theuser. For example, controller 100 may be configured to detect a lowpower level in battery assembly 88, a sensor assembly that has becomedisconnected from the patient, a malfunction in buttons 86, lostcommunications, etc. The indication provided to the user may be the sameas or different than the indication provided in response to the alarmconditions.

When patient monitor 22 is in communication with network 30, the primarycentral station may be configured to control some or all of thefunctions of the patient monitor. This enables a clinician to control aplurality of remotely distributed patient monitors from a singlelocation. In addition, a central station may be configured to enable aclinician to control all patient monitors in communication with thecentral station to function identically. Alternatively, the clinicianmay control each patient monitor to function differently.

In the exemplary embodiment, the primary central station is configuredand operable to change the variable parameter values which definenominal data ranges. Thus, the clinician can set or change the detectionof alarm conditions at the primary central station. Instructions enteredby the clinician at the primary central station are communicated tocontroller 100. The controller is configured to change the specifiedvariable value in response to the instruction, and to analyze the vitalsigns data using the new value. Similarly, the primary central stationmay be configured to communicate instructions to controller 100specifying what portions of the vital signs data should be analyzed. Forexample, it is known to those of skill in the art that a patient's heartrate may be determined from ECG data or from SpO2 data. Thus, where thepatient monitor is collecting both ECG data and SpO2 data from apatient, a clinician at the central station may specify which type ofdata the controller analyzes to determine heart rate.

In addition, since the central stations typically have greater dataprocessing capability than the patient monitors, the primary centralstation may be configured to analyze the vital signs data received fromthe patient monitor to determine additional information. For example,the primary central station may be configured to perform ST and/orarrhythmia analysis on the ECG waveform data, whereas controller 100 mayanalyze the ECG waveform to determine only the patient's heart rate. Ifthe primary central station detects an alarm condition as a result ofthe analysis, the alarm condition may be displayed on central stationmonitor 36. In addition, the primary central station may communicate thealarm condition to the patient monitor and instruct controller 100 topresent an indication of the alarm condition at the patient monitor. Byvarying where the vital signs data analysis occurs (at the centralstation or at the patient monitor), the patient monitor's resources maybe concentrated on collecting the vital signs data and presentinginformation to a clinician attending the patient.

The primary central station may also be configured to control both thetypes of information and the image displayed on display screen 84. Forexample, where the ECG sensor assembly includes a plurality ofelectrodes, the clinician at the primary central station may instructthe patient monitor to display the waveform from a particular one of theelectrodes, as shown in FIG. 18. Alternatively, the clinician mayinstruct the patient monitor to display the waveforms from a pluralityof the electrodes, as shown in FIG. 19. It will be appreciated thatcontroller 100 may be configured to control display screen 84 to displayany desired information or image format in response to instructionsreceived from the primary central station. Alternatively, the controllermay be configured to turn off a portion or all of the display screen inresponse to instructions from the central station.

As described above, the patient monitor and/or the primary centralstation may be configured to indicate an alarm condition, equipmentproblem, etc., with at least one of a visible indicator or an audibleindicator. For example, FIG. 20 illustrates an exemplary imagedisplayable on display screen 84 which indicates an alarm condition.Typically, the user-interface will include an icon or other indicia tospecify the cause of the alarm or problem (e.g., high heart rate, hightemperature, etc.).

The patient monitor and primary central station may be configured tocontinue presenting the indicator for a predetermined time period, orfor as long as the condition or problem persists. Alternatively, theindicator may be terminated after a specified period of time, even ifthe condition or problem has not ended. In the exemplary embodiment, theindicator also may be terminated (or suspended for a defined timeperiod) if the clinician acknowledges the indication at the patientmonitor and/or the primary central station. Thus, an alarm conditiondetected at the primary central station and communicated to the patientmonitor may be acknowledged at the patient monitor. The acknowledgementis communicated to the primary central station, which then terminatesthe indication. As a result, a clinician attending the patient need notleave the patient's location to return to the primary central stationand acknowledge the alarm.

Once communications are established between a patient monitor and aprimary central station of the exemplary embodiment, the patient monitorcommunicates all vital signs data to the primary central station and iscontrolled by the primary central station. While other central stationsalso may receive the vital signs data and send instructions for thepatient monitor (as will be described in more detail below), the primarycentral station maintains control of the patient monitor and isresponsible for providing the central monitoring. However, control andcentral monitoring of the patient monitor may be transferred to adifferent central station, in which case the different central stationis configured to take over communications with the patient monitor andassume control of the central station.

In the exemplary embodiment, a clinician may transfer control of thepatient monitor to a different central station by entering a transferinstruction at the patient monitor or at the primary central station. Ifthe clinician is at the patient monitor, controller 100 transmits thetransfer instruction to the primary central station, which responds bysending a list of central stations to the patient monitor. Thecontroller displays the list on display screen 84 to allow the clinicianto select the desired central station. Once the clinician makes aselection, the patient monitor communicates the selection to the primarycentral station, which sends a request to the selected central stationto take over the communications. If the selected central station isunavailable, the primary central station sends a notification to thepatient monitor so that the clinician can make another selection.Alternatively, the patient monitor may communicate with the selectedcentral station directly. However, if the clinician is at the primarycentral station when transferring control, the primary central stationsends a request to the selected central station to take over thecommunications, as described above. Once the selected central stationtakes over as the new primary central station, the patient monitorcommunicates all subsequent vital signs data to the new primary centralstation.

As mentioned above, communications dropouts between the patient monitorand the primary central station may occur for a variety of reasons. Oncea dropout occurs, the patient monitor begins attempting to restore thecommunications. However, during the dropout, the patient is notmonitored at the central station. Therefore, the patient monitor may beconfigured to detect when central monitoring has ended, and to takeadditional steps to minimize any disruption due to the dropout.

In the exemplary embodiment, the patient monitor is configured tofunction differently when out of communication with a central station.For example, controller 100 may disable buttons 86 (e.g., bydisregarding inputs at the buttons) when the controller is incommunication with a central station so that the functions of thepatient monitor can only be changed at the central station.Alternatively, the controller may suppress alarm indications at thepatient monitor when in communication with a central station. Similarly,the controller may turn off the display when in communication with acentral station to conserve battery power. The controller may beconfigured to perform the above steps either automatically, or inresponse to an instruction from the central station. However, thecontroller typically is configured to activate the buttons, the displayand the alarm indications when not in communication with a centralstation.

Furthermore, some embodiments of patient monitor 22 include a button 86operable by the patient to request clincian assistance (i.e., a “NurseCall” button). In such case, the patient monitor may be configured torespond differently to activation of the button depending on whether thepatient monitor is in communication with a central station. For example,the patient monitor may be configured to sound an audible alarm if thepatient monitor is not in communication with a central station, or toforward the request for assistance to a central station without soundingan audible alarm if the patient monitor is in communication with acentral station.

Similarly, when communications between the patient monitor and centralstation are lost, the patient monitor may be configured to automaticallyswitch from a centrally-monitored mode, in which the vital signs data iscommunicated to a central station that at least partially controls thepatient monitor, to a stand-alone mode, in which the vital signs dataare not communicated to a central station. Typically, the patientmonitor also is configured to automatically switch from the stand-alonemode to the centrally-monitored mode when the communications arerestored. In other words, the patient monitor may be configured toautomatically relinquish at least partial control of the patientmonitoring process when in communication with a central station, but toresume full control in the event communications are lost.

In addition to automatically switching between a stand-alone mode and acentrally-monitored mode, the patient monitor may also be configured totake any one or more of a variety of steps to return to thecentrally-monitored mode with minimal disruption. As described above forexample, the exemplary patient monitor is configured to automaticallyand continuously attempt to restore the communications during thedropout. Upon restoring a connection to physical data transportstructure 32, the patient monitor is configured to reestablishcommunications with a primary central station and, where possible, toconfigure the monitoring session without intervention by a clinician.

Nevertheless, the vital signs data are not communicated to the centralstation during the dropout. As a result, further analysis at the centralstation of the vital signs data received during the dropout cannot beconducted, and the vital signs data cannot be stored on database system40 for later access. Therefore, exemplary patient monitor 22 could beconfigured to store at least a portion of the vital signs data collectedduring the dropout, and then communicate the stored vital signs data tothe central station once the communications are restored. The vitalsigns data may be stored in memory device 102 and/or some other datastorage buffer. In any event, the data collected during a dropout periodwould not be lost.

It will be appreciated that, depending on the length of the dropout, thevital signs data collected may exceed the patient monitor's storagecapacity. Therefore, the patient monitor may be configured to store onlya portion of the vital signs data collected once it detects the dropout.For example, the patient monitor may be configured to begin storing thedata immediately after detecting the dropout, and then cease storing newdata once the memory device is full. Alternatively, the patient monitormay be configured to begin storing the data immediately, and once thememory storage is full, to begin storing subsequent data in place of theoldest stored data. As a further alternative, the patient monitor may beconfigured to store only data from selected sensor assemblies ratherthan all sensor assemblies.

As another alternative, the patient monitor may be configured to storeportions of the vital signs data which meet defined criteria. In theexemplary embodiment for example, controller 100 is configured toanalyze the vital signs data received during a dropout, and to detectthe occurrence of a medically-significant event based on the vital signsdata. The controller only stores data that corresponds to the occurrenceof a medically-significant event. Examples of typicalmedically-significant events include alarm conditions, arrhythmia,activation of the Nurse-Call button, etc. The amount of data stored mayvary depending on the event. Typically, a continuous sequence of data isstored from a point in time several seconds or minutes before the eventis detected to several seconds or minutes after the event ends. Thus,several running seconds or minutes of prior data are continuouslybuffered until an event is detected, at which point all or a portion ofthe data is stored until the event ends.

It will be appreciated that the criteria defining amedically-significant event may vary depending on the type of event, thetype of sensor assembly that collects the data, the condition of thepatient, the clinician's judgment, etc. The patient monitor may bepre-programmed with the criteria defining medically-significant events.Alternatively, the criteria for medically-significant events may beprogrammed into the patient monitor by the clinician or received fromthe central station. In any event, by storing only data corresponding tothe occurrence of medically-significant events, the patient monitor isable to conserve data storage capacity while ensuring that communicationdropouts do not prevent the primary central station from receiving themost important vital signs data.

Alternatively, or additionally, exemplary patient monitor 22 may beconfigured to selectively store data under other conditions. Forexample, controller 100 may store data at selected time intervals, or inresponse to an instruction from a clinician via buttons 86, etc. Thus,it will be appreciated that the patient monitor may be configured toselectively store data under any conditions as desired for a particularapplication.

In the embodiments described above, patient monitor 22 communicatescollected vital signs data to a single central station, referred toherein as the primary central station. Likewise, the patient monitor iscontrolled by the primary central station. However, in otherembodiments, the patient monitor may be configured to broadcast thevital signs data it collects to a plurality of central stations, and toreceive and execute instructions from a plurality of central stations.As a further alternative, the primary central station may be configuredto convey vital signs data received from a patient monitor to one ormore other central stations.

As shown in FIG. 21, exemplary primary central station 24 a isconfigured to receive vital signs data from patient monitor 22, and toforward the vital signs data to one or more secondary central stations24 b. The vital signs data received from the patient monitor may then bedisplayed at the secondary central station(s) as well as at the primarycentral station. Typically, the secondary central station communicates arequest to the primary central station to receive a particular patient'svital signs data. In response to the request, the primary centralstation is configured to continuously forward all vital signs data itreceives that is associated with the particular patient. In addition,instructions entered at a secondary central station are communicated tothe primary central station, which forwards the instructions to thepatient monitor for execution. Thus, from the point of view of aclinician monitoring the patient, a secondary central station providesthe same capabilities as the primary central station. However, somefunctions are performed only at the primary central station, such asstoring or archiving the vital signs data to database system 40,performing arrhythmia analysis, etc.

It will be appreciated that communicating the vital signs data to one ormore secondary central stations allows the patient's data to bemonitored by clinicians at plural locations within the hospital. Thus,there is no need for a clinician to travel to a different floor, or careunit, etc., of the hospital to view the data from a particular patient.Similarly, a clinician endeavoring to monitor a particular patient isnot restricted to a single location, but instead can monitor the patientfrom a variety of different locations.

In addition to providing central monitoring from multiple locations,secondary central stations 24 b may also be configured to provide afailsafe in the event of a failure involving the primary centralstation. Thus, in the exemplary embodiment, at least one of thesecondary central stations is configured to automatically attempt totake over communications with the patient monitor if communicationsbetween primary central station 24 a and the patient monitor are lost.The secondary central station may be configured to detect the loss ofcommunications from the primary central station in a variety of ways. Inthe exemplary embodiment, the secondary central station is configured todetect a loss of communications with the primary central station(even asudden, catastrophic one such as loss of power). In response to themessage, the secondary central station would then attempt to establishcommunications with the patient monitor. Additionally, the secondarycentral station is configured to monitor the communications it receivesfrom the primary central station, and if the primary central stationsuddenly stops communicating (e.g., due to loss of power, malfunction,etc.) for a defined period of time, the secondary central station isconfigured to attempt to establish communications with the patientmonitor. Alternatively, the patient monitor may be configured totransmit a request for communications to the secondary central stationin the event the primary central station stops communicating.

Once the secondary central station establishes communications with thepatient monitor, the secondary central station takes over the functionsof the primary central station. Alternatively, the clinician may beprompted to select a new primary central station for further monitoring.Where plural secondary central stations are monitoring the patientmonitor, the first secondary central station to establish communicationswith the patient monitor takes over as the primary central station. Thenew primary central station then begins forwarding the vital signs datareceived from the patient monitor to the remaining secondary centralstations. Thus, the patient continues to be monitored at a centrallocation staffed by clinicians, and the vital signs data collected fromthe patient continues to be stored for later retrieval.

As described above, patient monitor 22 and central stations 24 areconfigured to automatically establish and maintain communications whilethe patient monitor is monitoring a patient. However, patient monitor 22may also be operable to end the communications with the centralstation(s). This provides an intentional and controlled termination ofcommunications so that the patient monitor and/or the central stationsdo not automatically attempt to restore communications. In the exemplaryembodiment, the patient monitor is operable by a clinician (e.g., usingbuttons 86) to transmit an end-communications signal to the primarycentral station. The primary central station is configured to send aconfirmation of the end-communications signal to the patient monitor,which is displayed to the clinician at the patient monitor. The primarycentral station may also send a notification to the secondary centralstations, if any.

Once the end-communications signal has been received and confirmed, thepatient monitor may be powered down by the clinician without causing theprimary central station to report a loss of communications. The primarycentral station will of course detect the loss of communication, butwill be configured not to report this type of loss because it isexpected. Alternatively, the primary central station will terminate thecommunications after a defined delay period even though vital signs datawere still being received. If the patient monitor is still operating andcollecting data after the communications are terminated, the patientmonitor would be required to initiate the rendezvous process describedabove to resume centralized monitoring of the patient. Any monitoringparameters, alarm conditions, etc., that were changed at the patientmonitor in response to an instruction from the central station would bereset to the nominal default values stored by the patient monitor.Likewise, any monitoring parameters, alarm conditions, etc., that werechanged at the central station in response to an instruction from theclinician at the patient monitor, would be reset to the nominal defaultvalues stored by the central station.

As shown in FIGS. 1 and 2 and described above, patient monitor 22 b isconfigured to establish communications with a central station andcommunicate vital signs data via either one of output port 96 orwireless transceiver 104 (illustrated in FIG. 7). In addition, exemplarypatient monitor 22 b is configured to detect whether output port 96 isconnected to physical data transport structure 32 (either directly orthrough terminal server 42), and to switch automatically betweenwireless communications and wire communications depending on whether theoutput port is connected to the network structure. For example, wherepatient monitor 22 b is initially in communications with a centralstation via output port 96 and the output port is disconnected fromphysical data transport structure 32, then controller 100 is configuredto automatically associate with an access point and continue thecommunications with the central station via wireless transceiver 104.Similarly, where patient monitor 22 b is in wireless communications witha central station when output port 96 is connected to physical datatransport structure 32, controller 100 is configured to automaticallycease communicating via wireless transceiver 104, and instead tocommunicate with the central station via the output port. Thus, theclinician can select whether patient monitor 22 b communicates usingwire or wireless communications by connecting and disconnecting,respectively, output port 96 to physical data transport structure 32.

As mentioned above, patient monitor 22 may also be configured toestablish communications with a central station to download newerversions of the control software stored in memory device 102 andexecutable by controller 100. It will be appreciated that the downloadprocess may be carried out in any of a variety of different ways withinthe scope of the invention. It should also be understood that thecontrol software could be for any component of the patient monitor, suchas by way of examples, computer cards associated with any/all of thesensor assemblies (e.g. a pulse oximetry card, an NIBP card, etc.),computer cards associated with radio telemetry, etc.

In the exemplary embodiment, patient monitor 22 is operable by a user torequest a software update. In response to the user's instructions, thepatient monitor attempts to establish communications with one or morecentral stations, and transmits a query for new versions of the softwareto the central stations. The query is included as a part of the requestfor communications which the patient monitor broadcasts to the centralstations during the rendezvous process. Each central station respondingto the request indicates the version of the software stored at thecentral station. The patient monitor waits a defined period (e.g., 10seconds) to receive responses from the central stations, and thenselects a central station with the newest version of the software. Thus,even where the central stations have multiple versions of the software,the patient monitor is configured to determine which central station(s)has the newest version and to download the software from the centralstation with the newest version. This allows a system administrator tostore new versions of the software on just one or a few of the centralstations, and then operate the patient monitors to automatically findand download the newest software.

Once a central station with the newest version of the software isselected, the patient monitor transmits a request to the selectedcentral station to download the new software. The selected centralstation responds by transmitting the new software via either wire orwireless communications, depending on whether the patient monitor iscommunicating via output port 96 or wireless transceiver 104. Thesoftware download may be carried out using any of a variety of methodsor protocols, such as Trivial File Transfer Protocol (TFTP), etc.Typically, the patient monitor and selected central station verify thatthe software was accurately received at the patient monitor using one ormore of a variety of error-checking methods known to those of skill inthe art. Once the patient monitor receives the new software, controller100 updates the control software by installing the new software. Thecontroller may carry out this updating process for control software ofany of components of the patient monitor as described above.

As described above, the invention provides a system for continuouslymonitoring a plurality of patients at one or more central stations usinga plurality of portable patient monitors. The invention also provides amethod for monitoring a patient at a central location, as indicatedgenerally at 300 in FIG. 22. The method is implemented by softwarerunning on patient monitors 22, central stations 24, and/or othercomponents of system 20. The method includes, at step 310 establishingwireless communications between a patient monitor and a communicationsnetwork having at least one wireless transceiver and a plurality ofcentral stations. Then communicating a list of the plural centralstations to the patient monitor via the wireless transceiver, asindicated at step 320. Alternatively, the list of the plural centralstations may be provided to, or stored on, the patient monitor in otherways. In any event, method 300 proceeds with selecting, at the patientmonitor, one of the plural central stations, as indicated at 330. Thencollecting, at the patient monitor, vital signs data from a patient, asindicated at step 340. The vital signs data are communicated to thewireless transceiver, at step 350, and then communicated from thewireless transceiver to the selected central station, at step 360.

A further method for monitoring patients according to the presentinvention is indicated generally at 400 in FIG. 23. Method 400 includes,at step 410, establishing communications between a wireless patientmonitor and a central station adapted to receive vital signs data from aplurality of patients. Configuring the patient monitor to collect vitalsigns data from a particular one of the plural patients, at step 420.Communicating a list of the plural patients from the central station tothe patient monitor, as indicated at step 430. Alternatively, the listof patients may be provided to, or stored on, the patient monitor inother ways. In any event, method 400 continues at step 440 withidentifying, at the patient monitor, the particular patient.Communicating the identity of the particular patient to the centralstation, at step 450. Communicating the vital signs data collected fromthe particular patient to the central station, as indicated at step 460.Finally, associating, at the central station, the vital signs data withthe particular patient, as indicated at step 470.

Another method for monitoring patients according to the presentinvention is indicated generally at 500 in FIG. 24. Method 500 includes,at step 510, establishing wireless communications between a patientmonitor and a central station. Collecting vital signs data from apatient at the patient monitor, at step 520. Communicating the vitalsigns data from the patient monitor to the central station, at step 530.In the event that communications between the patient monitor and thecentral station are lost, detecting that loss of communications, at step540. Storing at least a portion of the vital signs data at the patientmonitor while the patient monitor is out of communications with thecentral station, as indicated at step 550. Restoring wirelesscommunications between the patient monitor and the central station, atstep 560. Then, communicating at least a portion of the stored vitalsigns data from the patient monitor to the central station, as indicatedat step 570.

Another method for monitoring patients according to the presentinvention is indicated generally at 600 in FIG. 25, and includesestablishing wireless communications between a patient monitor and afirst central station, as indicated at step 610. Collecting vital signsdata from a patient at the patient monitor, at step 620. Communicatingthe vital signs data from the patient monitor to the first centralstation, at step 630. So long as communications between the patientmonitor and the first central station are maintained, the patientmonitor continues to communicate the vital signs data to the firstcentral station, as indicated at 640. However, in the eventcommunications between the patient monitor and the first central stationare lost, then wireless communications are automatically establishedbetween the patient monitor and a second central station, as indicatedat step 650. Finally, communicating the vital signs data from thepatient monitor to the second central station, at step 660. It shouldalso be noted that when a clinician using the patient monitor transferscommunication to a different central station, there is a transition time(presently that duration is in the range of about 5-10 seconds). Duringthat transition time, the patient monitor could be configured to storedata for later uploading to the different central station chosen by theclinician.

Another method for monitoring patients according to the presentinvention is indicated generally at 700 in FIG. 26. Method 700 includes,at step 710, establishing wireless communications between a patientmonitor connected to a particular one of plural patients and a centralstation. Communicating the identity of the particular patient from thepatient monitor to the central station, at step 720. Collecting vitalsigns data from the particular patient at the patient monitor, asindicated at 730. Then, communicating the vital signs data to thecentral station, at step 740, and associating, at the central station,the patient monitor with the particular patient, as indicated at step750. So long as communications between the patient monitor and thecentral station are maintained, the patient monitor continues tocommunicate the vital signs data to the central station, whichassociates the vital signs data with the particular patient, asindicated at 760. In the event communications between the patientmonitor and the central station are lost for a period of time,reestablishing the communications between the patient monitor and thecentral station, at step 770. Then, automatically determining, at thecentral station, whether the patient monitor is still connected to theparticular patient, as indicated at step 780. Finally, if the patientmonitor is still connected to the particular patient, then associatingthe patient monitor with the particular patient.

In addition to the exemplary methods for monitoring patients describedabove, it will be appreciated that the configuration and operation ofsystem 20 is not limited to the exemplary methods as many variations andmodifications are possible within the scope of the invention. Further,system 20 may be configured and operated to monitor patients accordingto a variety of other methods within the scope of the invention.Therefore, it will be understood that all such methods, variations andmodifications are within the scope of the invention.

It is believed that the disclosure set forth above encompasses multipledistinct inventions with independent utility. While each of theseinventions has been disclosed in its preferred form, the specificembodiments thereof as disclosed and illustrated herein are not to beconsidered in a limiting sense as numerous variations are possible. Thesubject matter of the inventions includes all novel and non-obviouscombinations and subcombinations of the various elements, features,functions and/or properties disclosed herein. No single feature,function, element or property of the disclosed embodiments is essentialto all of the disclosed inventions. Similarly, where the claims recite“a” or “a first” element or the equivalent thereof, such claims shouldbe understood to include incorporation of one or more such elements,neither requiring nor excluding two or more such elements.

It is believed that the following claims particularly point out certaincombinations and subcombinations that are directed to one of thedisclosed inventions and are novel and non-obvious. Inventions embodiedin other combinations and subcombinations of features, functions,elements and/or properties may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such amended or new claims, whether they are directed to adifferent invention or directed to the same invention, whetherdifferent, broader, narrower or equal in scope to the original claims,are also regarded as included within the subject matter of theinventions of the present disclosure.

What is claimed is:
 1. A wireless medical telemetry system, comprising:at least one wireless patient monitor configured to monitor a patient bycontinuously collecting vital signs data from the patient; a firstcentral station associated with one or more wireless transceivers, andadapted to establish communications with the at least one patientmonitor and continuously receive the vital signs data therefrom via theone or more wireless transceivers; and a second central stationassociated with the one or more wireless transceivers, and adapted tocontinuously receive the vital signs data via the one or more wirelesstransceivers; where the second central station is configured toautomatically attempt to establish communications with the at least onepatient monitor and continuously receive the vital signs data in placeof the first central station in the event the communications between thefirst central station and the at least one patient monitor are lost. 2.The system of claim 1, where the second central station is configured tomonitor the communications between the first central station and the atleast one patient monitor.
 3. The system of claim 2, where the secondcentral station is configured to monitor the communications between thefirst central station and the at least one patient monitor by receivingthe vital signs data from the first central station, and toautomatically attempt to establish communications with the at least onepatient monitor if the second central station stops receiving the vitalsigns data from the first central station.
 4. The system of claim 1,where the at least one patient monitor is configured to transmit arequest to establish communications to the second central station viathe one or more wireless transceivers in the event the communicationswith the first central station are lost.
 5. The system of claim 1,further comprising a third central station associated with the one ormore wireless transceivers, and adapted to receive vital signs data viathe one or more wireless transceivers, and where both the second andthird central stations are configured to automatically attempt toestablish communications with the at least one patient monitor andreceive the vital signs data in place of the first central station inthe event the communications between the first central station and theat least one patient monitor are lost.
 6. The system of claim 1, wherethe first central station is configured to communicate instructions tothe at least one patient monitor to control the patient monitor, andwhere the second central station is configured to automatically attemptto assume control of the at least one patient monitor in the event thecommunications between the first central station and the at least onepatient monitor are lost.
 7. A method for monitoring a patient,comprising: establishing wireless communications between a patientmonitor and a first central station; continuously collecting vital signsdata from a patient at the patient monitor; continuously communicatingthe vital signs data from a patient at the patient monitor; continuouslycommunicating the vital signs data from the patient monitor to the firstcentral station; and if communications between the patient monitor andthe first central station are lost, automatically establishing wirelesscommunications between the patient monitor and a second central station,and continuously communicating the vital signs data from the patientmonitor to the second central station.
 8. The method of claim 7, furthercomprising monitoring, at the second central station, the communicationsbetween the patient monitor and the first central station.
 9. The methodof claim 8, where the step of monitoring includes receiving, at thesecond central station, the vital signs data from the first centralstation.
 10. The method of claim 7, where the step of establishingwireless communications between the patient monitor and the secondcentral station includes detecting, at the patient monitor, a loss ofcommunications with the first central station, and transmitting arequest to establish communications from the patient monitor to thesecond central station.